(a) Field
The invention relates to a thin film transistor and a method for manufacturing the same.
(b) Description of the Related Art
A liquid crystal display is one of the flat panel displays which have been most widely used. The liquid crystal display includes two sheets of display panels in which field generating electrodes, such as a pixel electrode and a common electrode, are disposed and a liquid crystal layer interposed therebetween. The liquid crystal display displays an image by applying a voltage to the field generating electrodes to generate an electric field in the liquid crystal layer, determining an orientation of liquid crystal molecules of the liquid crystal layer based on the generated electric field, and controlling a polarization of incident light.
In the liquid crystal display, each of the two field generating electrodes which generate the electric field in the liquid crystal layer may be disposed on a single one of the display panels, such as a thin film transistor array panel.
The thin film transistor array panel includes a plurality of thin film transistors, in which the thin film transistor is configured of a gate electrode connected to a gate line, a source electrode connected to a data line, a drain electrode connected to a pixel electrode, a semiconductor layer which is disposed on the gate electrode between the source electrode and the drain electrode, and the like, and transmits a data signal from a data line to the pixel electrode depending on a gate signal from the gate line.
A semiconductor is an important factor which determines characteristics of the thin film transistor. As the semiconductor, amorphous silicon has been mainly used; however, since the amorphous silicon has low charge mobility, there is a limitation in manufacturing a high-performance thin film transistor. Further, since the polysilicon has high charge mobility and the high performance thin film transistor is easily manufactured, but cost is increased and uniformity is reduced, there is a limitation in manufacturing a relatively large thin film transistor array panel.
Therefore, research into a thin film transistor using an oxide semiconductor which has the electron mobility and an on/off ratio of current higher than amorphous silicon, is cheaper and has the uniformity higher than polysilicon, has been conducted.